FIG. 7 shows a seat as typically used for a car composing a surface material 71 and a cushioning body 77 in accordance with the art. The surface material 71 composes a side surface member 72, a circumferential surface member 73 and a central surface member 74, and the side surface member 72, the circumferential surface member 73 and the central surface member 74 are corresponding to a side portion, a circumferential portion and a central portion of the seat, respectively. Each member of the surface material 71 is cut from a flat sheet material, and the surface material 71 is formed by stitching those members 72, 73, 74 so that a shape of the surface material 71 can be corresponding to a three dimensional shape of the seat.
The cushioning body 77 is covered with the surface material 71 having the same outline as the cushioning body 77. Then, the surface material 71 is connected with the cushioning body 77 by connecting a wire 78, which is provided in a gap formed in the cushioning body 77, and another wire 76, which is provided with a band cloth 75 stitched with the central surface member 74 and the circumferential surface member 73, through a hog-ring so that the surface material 71 can not be floated. The seat of the art is assembled in accordance with a manner as mentioned in the above.
It takes much time to cut a sheet material into those members of the surface material. Recently, a shape of a surface material used for a seat has been complicated, and in order to form such a surface material, the sheet material must be cut into members of the surface material having several shapes. Also, it is not suitable for mass production to connect the surface material 71 and the cushioning body 77 by use of the hog-ring, because workers must pay much time to assemble the surface material 71 and the cushioning body 77 in a work shop for carrying out such an assembling line work without a break.
In addition, when a person sits on the seat, the surface material is tensioned by a weight of the person. In the art, several textile materials typically used for the surface material can not be restored to an original state thereof when the person is away from the seat. Thus, the surface material is crumpled, and an external view as a quality of the seat is injured thereby.
In order to solve those problems, in a conventional technique, as shown in FIG. 7, a slab material 79 of an urethane foam having an excellent resiliency is bonded on a back surface of the surface material, and a thin textile material 80 is bonded on another surface of the urethane foam, in order to enhance resilient characteristics of the surface material.
However, it takes much time to fabricate such a surface material, and as a result, the surface material is expensive.
Also, for a seat used for a vehicle and a chair used in an office or as a furniture and the like (hereinafter simply written by a seat), in general, a resiliency is required to make a person comfortable when the person sits on the seat, and an appropriate hardness is also required to support a weight of the person.
In addition, in order to improve a shape-maintainability of the seat and an external view as a quality of the seat, it is desired to harden a side portion of the cushioning body of the seat.
However, in the seat composed and manufactured by according to the art, it is difficult to freely and partially control the hardness of the cushioning body thereof.
Therefore, an object of the present invention is to provide a seat wherein a surface material of the seat is integrated in one with a cushioning body thereof and a method for manufacturing such a seat.
Another object of the present invention is to provide a seat comprising a cushioning body composing of an upper layer and a lower layer wherein the upper layer which contacts with a person through a surface material is appropriately soft and the lower layer for supporting a weight of the person is appropriately hard, and is to provide a method for manufacturing such a seat.
Still another object of the present invention is to provide a seat comprising a cushioning body composing of an upper layer and a lower layer wherein a hardness of the upper layer is partially different, and is to provide a method for manufacturing such a seat.
Yet another object of the present invention is to provide a seat composing a surface material and a cushioning body integrated in one with the surface material wherein a constitution of the surface material is simplified, and is to provided a method for manufacturing such a seat.